After upgrade to Spring Boot 3.2, AOT failure "Code generation does not support ?"

[dmikusa]

I've recently upgraded an app from Spring Boot 3.1.8 to Spring Boot 3.2.3. The project is built with Gradle and uses Java 21. It has dependencies on Spring Data JDBC and has tests that mock our repositories with @MockBean.

After upgrading, when I run ./gradlew build I get this failure. The tests are all failing during the AOT code generation phase with this error.

Exception in thread "main" org.springframework.test.context.aot.TestContextAotException: Failed to generate AOT artifacts for test classes [<list of our classes>]
        at org.springframework.test.context.aot.TestContextAotGenerator.lambda$processAheadOfTime$5(TestContextAotGenerator.java:285)
        at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:986)
        at org.springframework.util.MultiValueMapAdapter.forEach(MultiValueMapAdapter.java:179)
        at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:243)
        at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:205)
        at org.springframework.test.context.aot.TestAotProcessor.performAotProcessing(TestAotProcessor.java:91)
        at org.springframework.test.context.aot.TestAotProcessor.doProcess(TestAotProcessor.java:72)
        at org.springframework.test.context.aot.TestAotProcessor.doProcess(TestAotProcessor.java:39)
        at org.springframework.context.aot.AbstractAotProcessor.process(AbstractAotProcessor.java:82)
        at org.springframework.boot.test.context.SpringBootTestAotProcessor.main(SpringBootTestAotProcessor.java:63)
Caused by: org.springframework.test.context.aot.TestContextAotException: Failed to process test class [<failing test class>] for AOT
        at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:322)
        at org.springframework.test.context.aot.TestContextAotGenerator.lambda$processAheadOfTime$5(TestContextAotGenerator.java:276)
        ... 9 more
Caused by: java.lang.IllegalArgumentException: Failed to generate code for '[[MockDefinition@5b5f61cc name = '', typeToMock = <Spring Data JDBC repository being mocked>, extraInterfaces = set[[empty]], answer = RETURNS_DEFAULTS, serializable = false, reset = AFTER]]' with type java.util.LinkedHashSet<?>
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator.generateCode(BeanDefinitionPropertyValueCodeGenerator.java:105)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertiesCodeGenerator.generateValue(BeanDefinitionPropertiesCodeGenerator.java:257)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertiesCodeGenerator.lambda$addConstructorArgumentValues$3(BeanDefinitionPropertiesCodeGenerator.java:179)
        at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:986)
        at java.base/java.util.Collections$UnmodifiableMap.forEach(Collections.java:1707)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertiesCodeGenerator.addConstructorArgumentValues(BeanDefinitionPropertiesCodeGenerator.java:176)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertiesCodeGenerator.generateCode(BeanDefinitionPropertiesCodeGenerator.java:126)
        at org.springframework.beans.factory.aot.DefaultBeanRegistrationCodeFragments.generateSetBeanDefinitionPropertiesCode(DefaultBeanRegistrationCodeFragments.java:176)
        at org.springframework.beans.factory.aot.BeanRegistrationCodeGenerator.generateCode(BeanRegistrationCodeGenerator.java:81)
        at org.springframework.beans.factory.aot.BeanDefinitionMethodGenerator.lambda$generateBeanDefinitionMethod$3(BeanDefinitionMethodGenerator.java:176)
        at org.springframework.aot.generate.GeneratedMethod.<init>(GeneratedMethod.java:54)
        at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:112)
        at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:89)
        at org.springframework.beans.factory.aot.BeanDefinitionMethodGenerator.generateBeanDefinitionMethod(BeanDefinitionMethodGenerator.java:169)
        at org.springframework.beans.factory.aot.BeanDefinitionMethodGenerator.generateBeanDefinitionMethod(BeanDefinitionMethodGenerator.java:89)
        at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.lambda$generateRegisterBeanDefinitionsMethod$2(BeanRegistrationsAotContribution.java:90)
        at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:986)
        at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.generateRegisterBeanDefinitionsMethod(BeanRegistrationsAotContribution.java:88)
        at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.lambda$applyTo$1(BeanRegistrationsAotContribution.java:73)
        at org.springframework.aot.generate.GeneratedMethod.<init>(GeneratedMethod.java:54)
        at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:112)
        at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:89)
        at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.applyTo(BeanRegistrationsAotContribution.java:72)
        at org.springframework.context.aot.BeanFactoryInitializationAotContributions.applyTo(BeanFactoryInitializationAotContributions.java:78)
        at org.springframework.context.aot.ApplicationContextAotGenerator.lambda$processAheadOfTime$0(ApplicationContextAotGenerator.java:58)
        at org.springframework.context.aot.ApplicationContextAotGenerator.withCglibClassHandler(ApplicationContextAotGenerator.java:67)
        at org.springframework.context.aot.ApplicationContextAotGenerator.processAheadOfTime(ApplicationContextAotGenerator.java:53)
        at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:318)
        ... 10 more
Caused by: java.lang.IllegalArgumentException: Failed to generate code for '[MockDefinition@5b5f61cc name = '', typeToMock = <Spring Data JDBC repository being mocked>, extraInterfaces = set[[empty]], answer = RETURNS_DEFAULTS, serializable = false, reset = AFTER]' with type ?
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator.generateCodeForElement(BeanDefinitionPropertyValueCodeGenerator.java:114)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator$CollectionDelegate.generateCollectionOf(BeanDefinitionPropertyValueCodeGenerator.java:351)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator$SetDelegate.generateCollectionCode(BeanDefinitionPropertyValueCodeGenerator.java:450)

> Task :processTestAot FAILED
10 actionable tasks: 1 executed, 9 up-to-date
      at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator$SetDelegate.generateCollectionCode(BeanDefinitionPropertyValueCodeGenerator.java:440)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator$CollectionDelegate.generateCode(BeanDefinitionPropertyValueCodeGenerator.java:334)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator.generateCode(BeanDefinitionPropertyValueCodeGenerator.java:132)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator.generateCode(BeanDefinitionPropertyValueCodeGenerator.java:102)
        ... 37 more
Caused by: java.lang.IllegalArgumentException: Code generation does not support ?
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator.generateCode(BeanDefinitionPropertyValueCodeGenerator.java:137)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator.generateCodeForElement(BeanDefinitionPropertyValueCodeGenerator.java:111)
        ... 43 more

It seems to be triggered by the @MockBean annotation. If I comment out that type, then I can get a clean build.

I don't know where that ? in the type is coming from as none of my repository types are using that. They are all pretty standard types, like...

public interface FooRepository extends ListCrudRepository<Foo, UUID>, PagingAndSortingRepository<Foo, UUID> {
}

Someone else mentioned getting the same issue and using @MockBean, but mocking different things. See here.

Thanks

[wilkinsona]

Duplicates #32195.

Some changes were made in Framework 6.1 so that this problem now results in a failure. Previously it resulted in some logging (at WARN level, IIRC) and the affected tests being skipped. You can now opt in to them being skipped by using @DisabledInAotMode.

[dmikusa]

Thank you for pointing me in the right direction, exactly what I needed to know.